1. Field of Art
The present invention generally relates to the field of signal detection and more specifically to using data from both directions of a bi-directional communication channel to enhance signal quality.
2. Description of the Related Art
Recent technological advancements have increased the use of speech communication applications, such as speech recognition, hands-free telephony and speech coding. These advancements have lead to increased use of voice activity detection (VAD) algorithms and processes. VAD processes detect the presence or absence of human speech from audio samples.
In particular, in hands-free telephone applications, VAD is used to control and reduce average bit rate and to enhance overall coding quality. Further, VAD processes are used to implement discontinuous transmission (DTX) in portable devices, which enhances system capacity and/or signal quality by reducing co-channel interference and power consumption. However, conventional VAD techniques separately process transmitted data and received data. Commonly, two independent VAD processes are used, one for the transmitted data and one for the received data.
However, because system parameters are constantly varying, conventional VAD techniques can erroneously classify speech and noise, and vice versa. In particular, in mobile environments, background noise is diverse and highly variable, and can lead to low signal-to-noise ratios (SNRs). In low SNR environments, existing VAD methods cannot distinguish between speech and noise when parts of the speech are below the noise threshold.